Bryan Mills (Liam Neeson) is a retired CIA operative called a "preventer", but most likely from the famed Special Activities Division. He has retired to spend more time with his 17-year-old daughter Kim (Maggie Grace), who now lives with his ex-wife Lenore (Famke Janssen) and her new wealthy husband Stuart (Xander Berkeley). When pop diva Sheerah (Holly Valance) comes to town, Bryan is hired for security. After the show, the diva is attacked, but Bryan disables the assailant and gets her safely out of danger. Thankful, the diva expresses some interest in Bryan’s daughter after learning that Kim wants to be a singer herself. The diva passes along her contact information.

The next day, Bryan discovers that Kim wants to take a vacation to Paris, France with her friend Amanda (Katie Cassidy). Despite his initial concerns about the trip, Bryan agrees to allow it, later discovering that their actual plan is to travel around Europe following U2. Arriving at the Paris airport, Kim and Amanda meet a charming Frenchman named Peter (Nicolas Giraud), who learns their address and reports it to an unseen associate.In the house, Kim receives a phone call from her father, which she answers in the bathroom. From the bathroom window she sees men entering the main room and abducting Amanda. Bryan is able to gain critical information about the kidnappers in the final moments after Kim is kidnapped by telling her to shout out everything about them that she notices. Briefly, Bryan talks to one of the kidnappers, warning him that he has acquired certain skills in his line of work and that unless Kim is released, he will pursue him and kill him, to which the kidnapper replies "good luck" before smashing the daughter's phone.

Exploiting his government contacts and the business connections of his ex-wife’s husband, Bryan travels to Paris to find her, informed that the kidnappers are Albanian sex traffickers and that he has only 96 hours to recover his daughter before she will disappear forever, and that the local leader is a man named Marko. He uses digital photos from the smashed remains of Kim's phone to locate Peter, who is killed by a truck while trying to escape. He manages to save one of the kidnapped girls from the Albanians and she discloses to him the address of the house where the kidnappers are holding other girls. Bryan finds the house and several other abducted women - including Amanda, who is dead from a forced overdose. Later, by torturing Marko, Bryan ascertains that Kim was sold to a man named Patrice Saint-Clair, who showed interest in making a profit from selling her. After wreaking havoc in the streets of Paris, Bryan is hunted by the French authorities, including Bryan's old ally Jean-Claude (Olivier Rabourdin), who wants him to return to the United States. Undeterred, Bryan forces Jean-Claude to give him Saint-Clair's location by shooting Jean-Claude's wife in the arm and revealing he knows Jean-Claude received bribes for overlooking the trafficking.

By impersonating Jean-Claude, Bryan gains entry to the building where new girls are being sold, and secures entry to one of the buyers’ viewing booths. He sees his daughter as she is displayed on the auction block. However, he is captured before he can engineer an escape for himself and his daughter. He manages to escape and find Saint-Clair, whom he kills after learning that his daughter is being taken by Qatari clients. Bryan manages to follow the car his daughter is being taken in to see her being taken away on a ship. He jumps on to the ship from a bridge and kills everyone in his way, finally freeing his daughter. Back in the US, Kim is reunited with her mother. Bryan introduces Kim to Sheerah, having arranged an audition with her vocal coach.